Pathogenicity of Yersinia enterocolitica Demonstrated in the Suckling Mouse

Area of Science:

• Microbiology
• Bacteriology
• Pathogen Detection

Background:

• Yersinia enterocolitica pathogenicity is primarily associated with the Vwa plasmid.
• Accurate detection of virulence factors is essential for identifying pathogenic strains and understanding disease transmission.

Purpose of the Study:

• To compare the sensitivity and consistency of various Yersinia enterocolitica pathogenicity tests.
• To evaluate the efficacy of in vitro assays against a biological model (suckling mouse test).

Main Methods:

• Comparison of an experimental suckling mouse intraperitoneal injection test with four plasmid-associated tests: adult mouse peroral exposure, adult mouse intraperitoneal injection, auto-agglutination, and plasmid detection by gel electrophoresis.
• Analysis of 35 clinical Y. enterocolitica strains from foodborne outbreaks.
• Sensitivity testing using isogenic plasmid-harboring (P+) and plasmidless (P-) Y. enterocolitica cells.

Main Results:

• The suckling mouse test demonstrated higher sensitivity and consistency in detecting the Vwa plasmid compared to in vitro methods.
• A bacterial population with as little as 0.1% P+ cells induced lethal infection in suckling mice, while in vitro tests required at least 10% P+ cells.
• In outbreak strains, auto-agglutination and gel electrophoresis tests alone were insufficient for evaluating virulence, with 17% showing discordant results.

Conclusions:

• The suckling mouse intraperitoneal injection test is a superior biological assay for Yersinia enterocolitica pathogenicity assessment.
• In vitro tests like auto-agglutination and plasmid detection are less sensitive and may not accurately reflect virulence alone.
• Accurate pathogenicity testing is critical for managing Yersinia enterocolitica in foodborne illness outbreaks.